Laravel框架Eloquent ORM简介、模型建立及查询数据操作详解

本文实例讲述了laravel框架eloquent orm简介、模型建立及查询数据操作。分享给大家供大家参考，具体如下：

注：以下知识点可能有不全面之处，望见谅

no.1eloquent orm简介

laravel所自带的eloquent orm是一个优美、简洁的activerecord实现，用来实现数据库操作
每个数据表都有与之相对应的“模型（model）”用于和数据交互

no.2模型的建立

最基础的模型代码如下:

namespace app;
use illuminate\database\eloquent\model;
class student extends model
{
 //指定表名
 protected $table = 'student';
 //指定id
 protected $primarykey = 'id';
}

将他创建于app目录下，命名为student.php

no.3查询数据

首先在查询之前，我先让你们看一下我的数据库

数据如上，然后查询

1.all方式

代码如下:

namespace app\http\controllers;
use app\student;
use illuminate\support\facades\db;
class studentcontroller extends controller
{
 public function orm1()
  {
      $students = student::all();
      dd($students);
 }
}

显示数据库里的所有数据

2.find方式

代码如下:

namespace app\http\controllers;
use app\student;
use illuminate\support\facades\db;
class studentcontroller extends controller
{
 public function orm1()
  {
      $students = student::find(1);
      dd($students);
 }
}

查找指定数据

3.findorfail方式

代码如下:

namespace app\http\controllers;
use app\student;
use illuminate\support\facades\db;
class studentcontroller extends controller
{
 public function orm1()
  {
      $students = student::findorfail(1);
      dd($students);
 }
}

如果他没查到指定的数据，那么他会报错，而find若是没有查到该函数，只会弹出一个null

4.查询构造器的使用

• 1.get方式使用

namespace app\http\controllers;
use app\student;
use illuminate\support\facades\db;
class studentcontroller extends controller
{
 public function orm1()
  {
      $students = student::get();
      dd($students);
 }
}

他会得到一个完整的数据信息，和原本的意义没有区别

• 2.first方式使用

代码如下:

namespace app\http\controllers;
use app\student;
use illuminate\support\facades\db;
class studentcontroller extends controller
{
 public function orm1()
  {
     $student = student::where('id','>',1)
     ->orderby('age','desc')
     ->first();
     dd($student);
 }
}

当id大于一的时候，获取一个最大值的age

• 3.where方式使用

代码如下:

namespace app\http\controllers;
use app\student;
use illuminate\support\facades\db;
class studentcontroller extends controller
{
 public function orm1()
  {
     $student = student::where('id','>',1)
     ->get();
     dd($student);
 }
}

• 4.chunk方式使用

代码如下:

namespace app\http\controllers;
use app\student;
use illuminate\support\facades\db;
class studentcontroller extends controller
{
 public function orm1()
  {
     $student = student::chunck(2,function($student){
  var_dump($student);
 });
 }
}

5.聚合函数的使用

• 1.count函数

代码如下:

namespace app\http\controllers;
use app\student;
use illuminate\support\facades\db;
class studentcontroller extends controller
{
 public function orm1()
  {
     $student = student::count();
     dd($student);
 }
}

• 2.max函数

代码如下:

namespace app\http\controllers;
use app\student;
use illuminate\support\facades\db;
class studentcontroller extends controller
{
 public function orm1()
  {
     $student = student::max('age');
     dd($student);
 }
}

• 3.min函数

代码如下:

namespace app\http\controllers;
use app\student;
use illuminate\support\facades\db;
class studentcontroller extends controller
{
 public function orm1()
  {
     $student = student::min('age');
     dd($student);
 }
}

• 4.avg函数

代码如下:

namespace app\http\controllers;
use app\student;
use illuminate\support\facades\db;
class studentcontroller extends controller
{
 public function orm1()
  {
     $student = student::avg('age');
     dd($student);
 }
}

• 5.sum函数

代码如下:

namespace app\http\controllers;
use app\student;
use illuminate\support\facades\db;
class studentcontroller extends controller
{
 public function orm1()
  {
     $student = student::sum('age');
     dd($student);
 }
}